The team tested out HP’s PageWide Enterprise Color MFP 586 and the HP Color LaserJet Enterprise M553 models, and found they were able to reverse engineer “.BDL” (bundle) extension files found in HP’s firmware.

After reverse engineering the code, the researchers were able to craft and upload crafted firmware files to discover where signature validation was taking place in order to bypass these protections.

Due to “insufficient solution DLL signature validation,” FoxGlove was then able to use this information to create malware specifically designed to exploit the printer ranges’ security weaknesses leading to remote code execution.

The security flaw was reported to HP on August 21st, 2017, is rated 8.1 on the CVSS scale.